Although mating surfaces of pairs of surfaces to be sealed, such as automotive engine component surfaces, appear to be smooth and flat, most frequently they are not sufficiently smooth to provide an effective seal. Accordingly, a gasket is required to be placed between such surfaces to provide an effective seal.
There are a wide variety of gasket designs, including metal gaskets, gaskets of fibrous materials, sandwich-type gaskets which combine a metallic core and compressible fiber-elastomer facing material laminated to the core, and so forth. As disclosed in U.S. Pat. No. 4,625,979, a wide variety of automotive gaskets are provided with sealing aids, such as elastomeric beads. Such beads are typically located on a face of the gasket by a variety of available processes. U.S. Pat. No. 4,659,410 describes a silk screening process for locating a sealing bead on a gasket surface.
As disclosed in U.S. Pat. No. 4,140,323, elastomeric beads can be deposited in embossments to confine the beads when the gasket is subjected to compression. The beads provide support for the embossment to avoid flattening of the embossment and thereby also enhance the effectiveness of the gasket in providing a seal.
Of course, for such beads to function most effectively, they must be accurately located within the embossments or accurately located on the surface of a gasket. In processes such as silk screening, therefore, it is necessary accurately to align the bead material as it is deposited and to assure a uniform deposit throughout the length of the bead. This is both laborious and expensive. Even though great care is exercised, it is still difficult to maintain accurate alignment between the sealing bead and the portion of the gasket on which the bead is deposited.
Therefore, it would be advantageous to provide an improved method for providing an elastomeric sealing bead for gaskets, especially for automotive gaskets.